Fan



0a. 26, 1937. M. F DOWELL 2,097,318

FAN

Filed April 26', 1935 Inventor:

Millard E Dowell,

b g 77 M34 His Abtovnqg.

Patented Oct. 26, 1937 UNITED STATES FAN Millard F. Dowell, Bridgeport, Conn., assignor to General Electric Company, a corporation of New York Application April 26, 1935, Serial No. 18,283

4 Claims.

My invention relates to fans, and particularly to a construction for resiliently supporting a fan'on its driving shaft which decreases the noise transmitted by the fan to the air.

In addition to the noise due to air turbulence, the noise which is transmitted from the fan is divided into two approximately equal parts. One part of this noise is transmitted as noise and vibration from the driving motor to the supporting base, and the other part is radiated from the fan blades to the surrounding air medium. By resiliently mounting the driving motor on its supporting base, the transmission of vibrations through the base can be decreased. This resilient motor mounting, however, does not afiect the transmission of vibrations from the fan blades to the air.

The object of my-invention is to provide an improved fan construction which will decrease the transmission of noise from the fan to the air. For a consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and the claims appended thereto.

In the accompanying drawing, Fig. l is a side elevation of a fan construction embodying my invention; Fig. 2 is a sectional side elevation showing the manner of supporting the fan shown in Fig. l on the driving shaft; Fig. 3 is a view illustrating one manner of assembling the fan shown in Fig. 1 on the driving shaft; Fig. 4 is a sectional side elevation of a modification of my invention; Fig. 5 is a front elevation partly broken I away of the modification shown in Fig. 4; Fig. 6 is a sectional side elevation of another modification of my invention; and Fig. '7 is a front elevation partly broken away of the modification shown in Fig. 6.

Referring to Figs. 1 and 2 of the drawing, the fan blades l are carried on arms 2 which are formed integral with a plate 3. This plate is pro vided with a central opening which fits over the end of a hub 4 and is held in place on the hub between a shoulder 5 and a spun-over portion 6. The construction described above is typical of a fan to which my invention may be applied.

The fan is resiliently supported on the driving shaft 1 of an electric motor, or other driving means, by an annulus 8 of resilient material such as rubber, which is fixed between the hub 4 and a sleeve 9. The sleeve 9 extends within the hub 4 and is rigidly fixed to, the driving shaft by a set screw l0 and can be considered as part of the driving shaft. The outer. surface of the annulus 8 is secured to the inner surface of the hub 4,

and the inner surface of the annulus 8 is secured to the sleeve 9. The annulus, therefore, provides a driving connection between the shaft and the fan.

In the operation of the fan, the annulus 8 being resilient in all directions prevents the transmission of noise and vibrations from the driving shaft to the fan and thereby prevents radiation of the motor noise and vibration from the fan to the air. The noise from the driving shaft includes bearing noise, magnetic noise from the motor which is mainly a torsional vibration, axial vibrations of the shaft due to pulsations of the end thrust, and radial vibrations due to unbalance of the driving motor. The resilience of the annulus 8 in axial and radial directions permits the axis of rotation of the fan to be displaced radially and also to be inclined with respect to the axis of the driving shaft. The radial displacement of the axis of rotation of the fan is due to the mechanical unbalance of the fan, which results in a force tending to cause the fan to rotate about its own center of mass. The inclination of tilting of the axis of rotation of the fan results from forces due to unequal loading of the fan blades which tend to incline the axis of rotation of the fan to a position in which the fan blades are equally loaded. One cause of this unbalance, which may be called load unbalance, is misalignment of the fan blades resulting from bending one of the fan blades forward or backward with reference to the other blades. The resilience of the annulus 8 prevents the transmission of the forces due to mechanical unbalance and load unbalance on the fan through the driving shaft to the driving motor since the fan rotates about an axis which produces dynamic and load balances. If these forces were transmitted to the driving motor, the noise from the motor would be increased. The resilience of the annulus 8 also provides a cushion support for the fan blades which prevents vibration of the fan blades.

The resilient support provided by the annulus 8 therefore decreases the noise which is transmitted from the fan to the surrounding air medium. This is particularly important as the noise would otherwise be carried by the air stream and be heard at points remote from the fan.

In Fig. 3 is shown one manner of assembling the resilient mounting for the fanshown in Figs. 1 and 2. A tube II of rubber or other similar resilient material having its normal cross section greater thanthe space between the sleeve 9 and the hub 4 is inserted through the hub so that both ends of the tube project beyond the hub. The sleeve 9 is then inserted within one end of the tube, as shown in Fig. 3, expanding the tube as shown, and causing the sleeve to be frictionally held within the tube. Tension is then applied to the other end of the tube. The tension causes the tube to elongate and thereby reduces the section of the tube so that the sleeve 9 is readily pulled within the hub. When the sleeve is in place within the hub, the tension on the tube is released, and the rubber expands to fill the space between the sleeve and hub, and is held in a state of compression between the sleeve and hub. The rubber fills the grooves l2 in the sleeve and hub, and the friction between the rubber and the sleeve and hub secures these parts together. The tube I I is then severed at the left-hand end of the sleeve and hub, leaving the mounting as shown in Fig. 2.

In the modification shown in Figs. 4 and 5, the plate 3 which carries the fan blades is placed over the end of a sleeve I3 which is adapted to be fixed to a driving shaft by a set screw l4. The sleeve I3 is of considerably less diameter than the opening l in the plate 3. The plate is secured to the sleeve l3 by an annulus N5 of rubberor other resilient material which is molded to the outer surface of the sleeve l3 and to the plate 3. The rubber fills the space between the opening l5 and the sleeve l3, and is secured to each side of the plate 3. The hub portion I! of the plate which is between the arms 2 is completely embedded in the rubber. The construction shown in Figs. 4 and 5 functions in the same manner as the construction shown in Fig. 2, but provides somewhat greater resilience in all directions. Due to the. portions H which are embedded in the rubber, the plate 3 is securely held by the rubber.

In Figs. 6 and 7, I have shown a modification of my invention in which four equally spaced metal springs I8 are used to resiliently support the fan on the driving shaft. In this modification the plate 3 which supports the fan blades fits over the end of a ring l9 and is held in place on the ring between a shoulder 20 and a spunover portion 2|. The springs I8 are provided with U- shaped portions 22 into which the ring I9 fits. The U-shaped portions are suitably secured to the ring. On either side of the U-shaped portion 22, the springs are provided with reverse curved portions 23, the ends 24 of which extend outwardly from the ring I9. Onone side of the ring I9, the ends 24 are shown'fitting within slots 25 in a shoulder 26 formed on a sleeve 21. On the other side of the ring IS, the ends 24 are secured by a spun-over portion 28 to an outwardly flaring portion 29 of the sleeve 21. The sleeve 21 is secured to the drive shaft 1 by a set screw 30. In this construction, the ring l9 and the U- shaped portions 22 of the springs l8 are spaced from the shaft, and the reverse curved portions 23 resiliently support the fan on the driving shaft. The reverse curved portions 23 are resilient in all directions, and the operation is similar to the construction shown in Figs. 1 and 2.

What I claim as new and desire to secure by Letters Patent in the United States is:

1. In a fan, a plate having a hub portion, fan blades carried by said hub portion, a driving shaft extending within and spaced from said hub, and an annulus of rubber secured to said shaft and said hub, the portion of said hub between thefan blades being enclosed in said annulus.

2. In a fan, a plate having a hub portion with arms extending therefrom, fan blades secured to said arms, a sleeve extending within and spaced from said hub, and an annulus of rubber secured to said sleeve and said hub, said hub being enclosed in said annulus between said arms.

3. In a fan having a hub and fan blades carried thereby, an annulus of rubber molded around said hubv and embedding the peripheral portion between said blades, said annulus being adapted to be connected to a shaft whereby it provides a resilient support for the fan on the shaft.

4. In a fan having a hub and fan blades carried thereby, an annulus of rubber secured to said hub and enclosing the peripheral portion thereof between said blades, said annulus being adapted to be connected to a shaft whereby it provides a resilient support for the fan on the shaft.

MILLARD F. DOWELL. 

